Cummins Diesel Forum banner

Cranks but doesn't start

678 views 8 replies 4 participants last post by  rebar 
#1 ·
Hey guys, this post has probably been on here before, so if I can be directed to another post about my question that would be fine. My problem is that my 97 12 valve doesn't start. It cranks but doesn't turn over and run. I just finished tabbing my KDP, replaced my front crank seal, gasketed my front timing cover and installed a new radiator. Could my crank sensor be bad? Could I have a short in my ground? Could my PCM be bad? I'm going to have my batteries tested and charged tomorrow. The batteries are a little low on voltage, but they're brand new (installed this summer). The truck sat for about 32 days as I was working on it. Also I gaped the crank sensor at about .05 in". I had trouble getting the sensor in and it touched the harmonic balancer. I measured some plastic cards with a caliper to see if I can use the plastic cards as a non-magnetic gaping tool.
 
#2 ·
Hey guys, this post has probably been on here before, so if I can be directed to another post about my question that would be fine. My problem is that my 97 12 valve doesn't start. It cranks but doesn't turn over and run. I just finished tabbing my KDP, replaced my front crank seal, gasketed my front timing cover and installed a new radiator. Could my crank sensor be bad? Your engine speed sensor (it is not a crank sensor) does not even have to be installed for the engine to run. That' not itCould I have a short in my ground? HUH?Could my PCM be bad? No, the pcm isn't necessary for the engine to run either. You do not have a computer controlled engine.I'm going to have my batteries tested and charged tomorrow. The batteries are a little low on voltage, but they're brand new (installed this summer). The truck sat for about 32 days as I was working on it. Also I gaped the crank sensor at about .05 in". I had trouble getting the sensor in and it touched the harmonic balancer. I measured some plastic cards with a caliper to see if I can use the plastic cards as a non-magnetic gaping tool.
The sensor should be gapped at .050 inch but as I said, that won't keep the engine from running.

Have you confirmed the injectors are getting fuel? Crack a injector nut and see if any comes out when you crank the engine. BTW, if it cranking it is turning over. No fuel? Make sure the FSS is pulling up. If it is pulling up do some research about air in the suction side of the lift pump, specifically Joe G's writeup.
 
  • Like
Reactions: kripakm
#5 ·
So if the crank/speed sensor isn't gaped correctly, than what happens.
One more time, it is not a crank sensor. It is a speed sensor. As has been posted only about a thousand times and is covered in the factory service manual (I"ll bet you don't have one) it sends a signal to the PCM that sends signals to the tach, voltage regulator and the automatic transmission. Gapped has two Ps, gaped has an entirely different meaning.
 
#4 ·
It will still start and run without the CPS/ESS, that function controls the charging AC and a few other things.

Take a bungee cord or wire and pull the FSS up and then try to see if it will run.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top